Child resistant closures are well-known and understood to be effective in preventing inadvertent access to potentially dangerous materials such as medications by children. However, inclusion of the child resistant feature on containers is costly, and all too often, makes it difficult and frustrating for an adult user to open the container, especially an adult who has suffered a loss of manual dexterity, as by arthritis. Because of deteriorating health, elderly persons tend to rely on medication more than the average person. The elderly may also tend to have impaired manual strength and dexterity. Due to the difficulty encountered by such persons in opening child-resistant packages, many elderly persons request a non-child resistant substitute. Alternatively, when medications are purchased in child resistant packages by older adults, the packages are oftentimes not reclosed by the user thus defeating the purpose of the child resistant feature.
The aforementioned problems are generally recognized by the packaging industry, particularly in connection with packaging for the pharmaceutical industry. Attempts to deal with this problem are also disclosed in the patent literature. For example, U.S. Pat. No. 3,514,003 granted to Fitzgerald on May 26, 1970 teaches a two-piece closure having a selectably engageable locking device which is engaged or disengaged by axial movement of a collar member relative to a cap member. The cap and collar members have respective sets of teeth which interlock when the collar member is moved axially upwardly into its uppermost position. The neck of the bottle also includes teeth which engage the collar member when the collar member is in the uppermost position, thus preventing rotation of the closure. To unlock the closure, the collar member is slid downward and out of engagement with the cap member. This closure visually reveals that the collar member may be moved out of engagement with the cap member. Accordingly, a child having sufficient strength to disengage the collar member may have sufficient intellect to defeat the interlocking engagement and remove the closure. Moreover, the disclosed closure arrangement is not readily adaptable to commonly available bottles and vials, such as those typically used by pharmacists for dispensing prescription medications.
Another attempt to overcome the aforementioned problem is disclosed by Do Le Minth in U.S. Pat. No. 5,148,931, granted Sep. 22, 1992, which teaches a two piece closure having two sets of axial channels on an inner cap and two sets of protrusions on an interior surface of an outer cap. The closure is opened by aligning the protrusions on the outer cap with the proper set of channels on the inner cap, pulling the outer cap up relative to the inner cap, and rotating the outer cap so as to interlock the outer and inner caps. Disadvantageously, the disclosed arrangement is mechanically complex, requiring the consumer to follow a lengthy procedure to return the closure to the child resistant state, if required. Moreover, the complicated closure structure is difficult and expensive to fabricate.
It is thus desirable to provide a closure device which is selectively convertible between a child resistant configuration and an easily openable configuration allowing the user to choose the type of closure dependent upon the particular situation and environment in which the container is used.